Almost all life on the planet is dependent on six inches of top soil and rain. Add in the miracle of photosynthesis, says Master Gardener Janet Miller, and the summer gardener is in business.

Miller, the head gardener at Our Garden, was the guest speaker at the opening day at the new Our Garden, our larger demonstration garden at Wiget Lane and Shadelands Drive. The garden is a joint project of the Contra Costa Master Gardeners and the Bay Area News Group. This is the fifth season for the demonstration project that also helps feed the hungry. Classes are 10-11 a.m. every Wednesday through October, and are free.

Miller spoke on preparing our gardens for the spring and summer. Here is what she had to say.

The best season

Summer is the time when we get to grow our favorite crops, Miller says -- tomatoes, peppers, squash, beans, melons, cucumbers, basil and much more. There are more things you can grow in the winter, but the summer garden has our favorites, plus it grows very quickly.

Length of day and the angle of the sun are at their peaks, so there is lots of photosynthesis going on. Crops mature faster and we are able to get high yields in small spaces.

In the spring and summer so many things are blooming that we can have lots of beautiful herbs and flowers in and around the vegetable garden, attracting pollinators and birds, which help pollinate the vegetable garden.

Planning

When selecting a site for your garden, look for a place that has eight hours of sun, is easily accessible, relatively level with good drainage and close to water.

Plan your garden on paper first.

Beds should be narrow enough that you can reach into the middle of the bed without having to step on the soil.

Choose vegetables that you like to eat. Nothing is sadder than having a bumper crop of vegetables you don't like.

Preparing the soil

Vegetable crops have short life spans, but the hypergrowth they undergo requires high levels of nutrition in the soil. Nurturing the soil is the first and best step.

Test your soil, either with a home test from a nursery, or through a lab for a more extensive analysis.

In nature, Miller says, it takes 500 years to grow an inch of topsoil. Obtaining rich, fertile soil isn't something you're likely to achieve in a single season. It is an ongoing process. But the more that your improve the health of your soil and the microbial life in it, the better your garden will do.

Deep soil prep

Before working on your beds, make sure the moisture content is correct before digging. Too wet or too dry will do more harm than good. The soil should be the consistency of a damp sponge.

Double-digging is a method to loosen soil up to 24 inches down, creating tiny spaces in the soil for air and water. You'll dig a trench across the bed 12 inches deep, set aside the excavated soil and then use a garden fork to loosen the soil another 12 inches. Dig a second trench next to the first and use the soil you are digging out to fill the first trench. Repeat until the entire bed has been dug and forked, using the dirt from the first trench to fill in the last.

After digging the bed, add compost and fertilizer to add another six inches to the soil. Rake smooth, lightly water and you're ready to plant.

Use a high quality bagged compost or, better yet, make your own.

Add fertility as needed. Vegetable crops are using a lot of the macro and micro nutrients in the soil, which must be replenished.

The Bay Area's heavy clay soils are a mixed blessing. They contain a lot of wonderful micronutrients, but they don't give them up easily. To help with that, add compost. The more organic matter you put in the soil, the more nutrients become available to the plants.

Planting

Use offset grid planting instead of row planting. It allows you to grow more plants in a smaller space, and it also creates a microclimate around the plants. The leaves of the plants work together to shade the soil, protecting it from UV rays, and they reduce evaporation and weeds.

Crop rotation is essential, but it doesn't have to be a big production. You can even rotate crops in the same bed. Rotation of plant families prevents the buildup of soil-borne pathogens.

Use trellises and stakes to save room and grow more plants. Don't grow horizontally if you can grow vertically. Twining and vining crops such as tomatoes, squash, cucumbers and pole beans take up far less space when give a structure to climb on, Miller says.

If space is an issue, consider planting determinant tomatoes that grow to a prescribed size and are easier to stake.

Try intercropping -- planting early maturing plants between the rows of later maturing crops. Grow radishes, green onions, spinach and leaf lettuces among the tomatoes and peppers. The faster maturing crops will be harvested and out of the way before the slower maturing ones become very large.

Plant tall crops such as corn, pole beans and indeterminate tomatoes on the north side of the garden so they don't shade low growing crops.

Longer maturing plants benefit from getting a head start in the house, a greenhouse or nursery.

Protect young seedlings with shade cloth, and use Remay or floating row cover to protect young plants from birds and flying insects that love to eat young tender greens.